The Development of a Glass Matrix Inorganic Non-Metal Self-Lubricating Composite Coating and the Study of its Tribological Characteristics

A self-lubricating composite coating was prepared by melting method. The glass matrix was used for skeleton of this coating, which consists of BaO (16.6) , Si02 (45.8) , Cr2O3 (9.1) , K2O (10.3) , CaO (6.3) , CaF2/BaF2 (8.8) and CeO2 (3.0) . In order to improve the binding strength between the coating and substrate, a thick intermediate layer between the substrate and coating was added, the composition of this layer is BaO(28.8), SiO2 (27.9) , Cr2O3 (29.1) , CaO (2.58) , Z nO (3.60) , MoO3 (1.36) , Bentonite (2.91) and B2O3 (3.74) . The friction testing results showed that the anti-friction ability was increased by adding a small amount of fluoride into the coating. The fluoride reacted with silicon to form volatile matter under high temperature. Some bulbes were formed in the coating by cooling some of the volatile matter. The bulb distribution could be changed by adding rare earth oxide (CeO2) . It is suggested that the bulbes can break off or decrease the crack extension. The extension degree and pathway of crack depend on the bulbes' size and distribution, so under a given stress, the sizes of fracture particles are also different. The bulbes distribution is the best when CeO2 content is 3.0%. Under this condition, the resulted friction induced fracture particles may fall in the microvoids to roll. . Since the rolling, replaces part of sliding, the friction coefficient decreases "when the CeO2 content is less or more than 3.0%, because the abrasive dust' size is smaller or bigger than microvoids size, the friction coefficient ,ean not be changed. The liquid which exists in microvoids can bear the part of loadr ,therefore the friction coefficient further decreases. The test results indicated that the self-lubricating composite coating in which the CeO2 content is 3.0% possess good friction-wear characteristics in the HCl'and NaOH solutions.